1. Field of the Invention
This invention generally relates to a camera module, and more particularly to a packaging structure of a camera module.
2. Description of Related Art
Digital cameras have been widely used in our daily life. Because more and more customers are purchasing the digital cameras, how to simply the packaging process is an important issue for mass production.
The cost and quality of the digital cameras partially depend on the structure and method of packaging. FIG. 1 shows a traditional camera module. As shown in FIG. 1, a traditional camera module includes a holder 100 to hold a lens member 102 on its upper portion. The holder 100 also has a lower portion. There is an image sensing device 106 such as a CMOS image sensing device on the printed circuit board (PCB) 104 and inside the upper portion of the holder 100. CMOS image sensing device 106 is connected to the PCB 104 via the conducting line 108 by wire bonding. The holder 100 is fixed on the PCB 104 via a fixing member 112. If the PCB is a flexible PCB, then a hard plate 110 can be disposed on the other side of the flexible PCB corresponding to the image sensing device 106 in order to enhance the mechanical strength.
Another conventional method is to use the ball grid array (BGA) to package the chip on the circuit board. FIG. 2 shows the cross-sectional view of the image sensing device and signal processing device packaged on the circuit board by BGA. Referring to FIG. 2, the image sensing device 196 and the signal processing device 108 are packaged on the two sides of the circuit board 104 by BGA 114 and 116. The circuit board 104 covers the bottom of the holder 100.
FIG. 3 shows the cross-sectional view of the image sensing device and signal processing device packaged on the circuit board by BGA and wire bonding. Referring to FIG. 3, the image sensing device 106 is connected to the circuit board 104 via the conducting line 110 by wire bonding. The image sensing device 106 is packaged on the circuit board 104 by BGA.
During the packaging process, the particles or dust are easy to fall to the surface of the image sensing device 106, those particles will affect the quality of the image. To prevent the particles from attaching the image sensing device, a glass cover including a glass layer 120 covers the image sensing device 106 as shown in FIG. 4.
However, the glass cover will increase the packaging cost. Further, the image sensing device 106 and the signal processing device 108 have to be packaged on the two sides of the circuit board. This packaging process is costly and complex. How to simplify the packaging structure and to prevent the particles from attaching the image sensing device 106 is an important issue to the camera module manufacturers.